Patent GB-678229-A (GB)
Title: Improvements in or relating to the sheathing of cables
IPC: B23K20/00
Filed: 1949-12-15
Abstract: 678,229. Making electric conductors. ALUMINUM CO. OF AMERICA. Dec. 15, 1949 [Jan. 8, 1949], No. 32212/49. Classes 83 (ii) and 83 (iv). Rolling; drawing.-A method of sheathing cables comprises threading a cable loosely through a tubular metal sheath, securing the cable and tube at one end thereof, reducing the tube diameter and wall thickness to elongate the tube without clamp - ing the reduced tube and interior cable, supplying additional cable for the elongated tube and sinking the reduced tube on the cable without any relative axial movement between the cable and the reduced ' tube. In an embodiment the apparatus comprises a rotary ballreducing mill 10, one or more drawing dies 12 and a power-driven block 14. The mill 10 includes a rotatably mounted ball housing 16 driven by an electric motor 20. A cable 32 to be sheathed passes through the mandrel 26, mandrel nose 29 and the sheathing 30, 31 to the reduced end of which it is attached. The sheathing is fed by a pusher head 34 operated by a powerdriven lead screw 35. In operation the mill 10 and pusher head 34 are actuated to reduce a short length of sheathing 31 to which the cable 32, already inserted within the mandrel 26, is attached and the mill is again actuated to provide sufficient reduced sheathing 31 to reach the block 14. The mill is stopped and the end of the sheathing is swaged down and threaded through the drawing dies 12 and attached to the block 14. The block 14, mill 10 and pusher head 34 are then actuated in timed relationship to roll the sheathing and sink it on to the cable 32. An alternative form of tube reducing mechanism comprises segmental rolls 46 supported within a saddle member 39 reciprocated on a base 40 by a motordriven crank 44 and connecting-rod 45. The rolls 46 are secured on shafts 50 having gears 52 engaging racks 53. A tubular mandrel 55 has a tapered nose 60 and in front of its clamped rearward end is an indexing head 58 comprising a crank secured to the mandrel and coupled to a bell-crank lever 68. If desired, the indexing head 58 may be clamped to the metal sheathing 48. The sheathing is fed by reciprocating jaws 74, 75, the former being operated to grip the work by a cam 82 on a lever 80 coupled to a pivoted yoke 85, the lower end of which embraces an operating rod 90 extending rearwardly from the saddle 39 to the bell-crank 68. The yoke 85 and bell-crank 68 are operated by collars 104, 106 and 100 and 102, respectively. In operation, the tubular sheathing 48 is fed over the mandrel 55, through the jaws 74 and 75 and between the segmental rolls 46, the working faces of which have tapered grooves 47 relieved at 49. Towards the end of the forward movement of the saddle and after the rolls have reduced and elongated an increment of the bloom the collar 100 engages the bell-crank 68 and causes the mandrel and the tubular sheathing to rotate through 30 degrees. On the return movement of the saddle the rolls are swung up the tapered reduced tube, so smoothing and eliminating any fins. Towards the end of the return stroke, collar 106 strikes and rotates the yoke 85, causing the cam link 80 to force the upper chuck 74 downwardly to grip the tube between the chucks 74 and 75 and the remaining rearward movement of the saddle advances the tube 48 a small increment. The collar 102 returns the indexing head 58 to its original position on the rearward movement of the saddle and the collar 104 returns the yoke including the slide 73 and jaws 74 and 75 to their original position on the forward stroke of the saddle. Compression springs may be provided to ensure separation of the jaws. The rotational indexing of the tubular sheath should not exceed 360 degrees and may include angular step indexing up to 360 degrees in total angular displacement. A surplus of reduced sheathing and cable must be provided between rolls and the sinking dies 37 to permit continuous operation. Specification 333,281, [Class 83 (iv)], is referred to.